06-Swift 字典的使用

一、字典的定义

//可变字典，用泛型定义字典类型，当然类型定义可以省略
var dic11:Dictionary<Int,Int> = [0:1,1:2]
dic11[1] = 3     //修改字典内容
dic11    //[0: 1, 1: 3]

//不可变字典
let dic12:[String:Any] = ["a":4,"b":5,"c":6,"d":"1"]

二、字典元素的基本操作

• 任意值类型通常用 Any,而不是 NSObject

var dic21:[AnyHashable:Any] = [1:1,2:2,"a":"a","b":"b"]

• 增加元素

dic21["c"] = 3
dic21   //["b": "b", "a": "a", 2: 2, 1: 1, "c": 3]
dic21["a"] = 1
dic21   //["b": "b", "a": 1, 2: 2, 1: 1, "c": 3]

通过这种方式，如果字典中存在某个 键-值，就进行修改，如果不存在就进行添加此 键-值

• 删除元素

dic21.removeValue(forKey: "a")

或

let index = dic21.index(forKey: "a")
dic21.remove(at: index!)

结果为：

dic21   //["b": "b", 2: 2, 1: 1, "c": 3]

• 改元素

dic21[2] = "b"
dic21   //["b": "b", 2: "b", 1: 1, "c": 3]
dic21.updateValue("a", forKey: 1)
dic21   //["b": "b", 2: "b", 1: "a", "c": 3]

• 查元素

dic21[1]    //"a"

三、 字典的基本操作

var dic31:[AnyHashable:Any] = [1:1,2:2,"a":"A","b":"B"]

• 字典的遍历
• 遍历所有键

for key in dic31.keys {
    print(key)
}

• 遍历所有值

for value in dic31.values {
    print(value)
}

• 遍历所有键值

for (key,value) in dic31 {
    print(key,value)
}

• 字典的合并，通过遍历完成

var dic32:[AnyHashable:Any] = [1:2,2:3,"aa":"a","bb":"b"]
//将字典 dic31 和 dic32 合并，若有相同键，则保留 dic32 中的键值
for key in dic32.keys{
    dic31[key] = dic32[key]
}
dic31   //["b": "B", "a": "A", 2: 3, "aa": "a", 1: 2, "bb": "b"]

四、补充:扩展

extension Dictionary{
    static func + (dic1:inout Dictionary,dic2:inout Dictionary) -> Dictionary {
        for key in dic2.keys {
            dic1[key] = dic2[key]
        }
        return dic1
    }
}
var d4 = [1:1,2:"a"] as [Int : Any]
var d5:[Int : Any] = [3:1,4:2]
d4 + d5     //[2: "a", 3: 1, 1: 1, 4: 2]

两个相加的字典 键值 类型必须要一致才可以。